1. Field of the Invention
This invention relates to a novel process for separating fatty materials, such as fatty acids, from supported nickel catalysts. More specifically, the process involves subjecting the supported nickel catalyst containing the fatty material to supercritical fluid extraction, separating the fatty material and supported nickel catalyst and recovering same.
2. Description of the Prior Art
Supported nickel catalysts are utilized in numerous hydrogenation processes where low IV (iodine value) fatty products, i.e., products which are completely or essentially completely saturated, are desired. A considerable amount, sometimes up to about as much as 60 percent by weight, fatty material can be associated with the supported nickel catalyst or supported nickel catalyst and clay/earth mixtures. This can result in a substantial reduction in the yield of the process. The presence of fatty materials with the supported nickel catalyst also significantly impairs the catalyst activity so that it is impractical to recycle the catalyst. The presence of these fatty products even complicates processing the catalyst for recovery of the nickel value.
Procedures for the recovery of fatty materials from bleaching earths and clays are known. One such process for the recovery of polymeric fatty acids is described in U.S. Pat. No. 3,873,585. Also, in U.S. Pat. No. 4,049,685 a process for washing fatty acids from spent clay with aqueous alkali at elevated temperatures while maintaining a specified pH of 5-6.5 is disclosed. U.S. Pat. No. 4,110,356 describes a procedure for deoiling spent clay by slurrying the spent clay with aqueous alkali at a temeprature of at least 80.degree. C. and with a water to clay ratio of about 2-6:1. Similarly, U.S. Pat. No. 4,283,346 discloses the recovery of oil from clays by alkali treatment under high temperature and high pressure followed by the addition of an acid. A process for extracting residual vegetable oil contained in spent bleaching clays with an aliphatic hydrocarbon solvent and then reprocessing the bleaching clay for use is described in U.S. Pat. No. 4,285,832.
Procedures for the extraction of various fatty materials utilizing supercritical fluids are also known and such processes are described in U.S. Pat. Nos. 3,969,382, 4,156,688, 4,250,331, 4,280,961 and 4,422,966. The regeneration of adsorbents by removal of the adsorbate by contacting with a supercritical fluid is described in U.S. Pat. Nos. 4,061,566 and 4,124,528.
It would be highly advantageous to have a process whereby fatty materials could be readily removed from spent supported nickel catalysts and mixtures of such catalysts with clays and/or earths such as are employed for bleaching, deodorization and to assist in filtering. It would be even more desirable if an extraction process utilizing supercritical fluids were available wherein spent supported nickel catalysts obtained from various fatty processes could be treated to extract the adsorbed fatty material and if both the fatty material and catalyst could be recovered and subsequently used.